Recent stators have separate coil windings for each pole blade for increasing the winding density. it is a general practice in the art to adopt a Y-configured connection for this type of stator in order to reduce circulating current occurred due to unbalance among individual coil windings.
As the Y-configured connection, it is known to use a connection in which some of the coil windings have one ends thereof bundled together with regard to a same phase and the other ends thereof bundled together with those of the other coil windings regardless of difference in phase, and then are subjected to a connecting process by means of soldering, brazing or the like; a connection utilizing a printed board provided with printed wiring; a connection utilizing a multi-layered copper-bar board; and the like. The connection utilizing the multi-layered copper-bar board comprises a conductive board connected to the ends of coil windings of the same phase and a conductive board connected to the other ends of the coil windings in common regardless of difference in phases with an insulating material interposed therebetween (see, for examples JP A 6-233483).
Unfortunatelye however, the aforementioned connection through soldering or brazing the bundles of coil winding ends is performed by manual work which requires a great amount of time and effort. In view of a current capacity of a copper foil, the connection utilizing the printed board is not suitable in general for a large size stator which requires high current flowing therethrough.
The connection utilizing the multi-layered copper-bar board is constructed such that conductive boards are laminated by way of interposing an insulating material therebetween, so that the overall dimensions tend to increase with respect to a direction in which the boards are laminated. In addition, the conductive board is formed by pressing a copper sheet, requiring a press machine and a die for each frame. Consequently, the equipment for preparing this type of connection is complicated and large on scale.